Prior studies of black-white differences in hypertension and coronary disease have compared racial groups from markedly different socioeconomic and educational backgrounds. This project has, as its overall goal, the examination of the natural histories of coronary artery disease and hypertension in cohorts of black and white men of identical education and occupations. A cohort of 435 black physicians, alumni of the Meharry Medical College, will be compared with those of a cohort of 573 white physicians, alumni of the Johns Hopkins University School of Medicine. The present study has four specific aims. First, the prevalence and incidence of coronary artery disease, hypertension and other cardiovascular diseases will be compared using standardized endpoint criteria. Second, the prevalence of cardiovascular risk factors in midlife will be compared between cohorts, including smoking, diabetes, family history, dietary factors and lipoprotein cholesterol levels. Third, the youthful predictors of midlife cardiovascular risk factors will be determined using baseline data collected by identical protocols in the two cohorts between 1957 and 1965. Finally, the youthful risk factors will be related to the incidence of disease in midlife in the two cohorts to identify differences in significance, independence and relative importance of risk factors in black versus white. This study, a collaborative research effort between the Meharry Medical College and the Johns Hopkins School of Medicine, represents one of the few, if any, long term prospective studies of cardiovascular disease in middle-class blacks and whites of similar education and occupation, in whom both youthful and midlife risk factors will have been assessed. Knowledge regarding black-white differences in the course and causes of hypertension and coronary artery disease is needed to develop effective treatment and prevention strategies for both black and white Americans.